<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      button {
        width: 300px;
        height: 100px;
        font-size: 50px;
      }
    </style>
  </head>
  <body>
    <button class="ikun01" onclick="alert('hello ikun01')">行内</button>
    <button class="ikun02">本页</button>
    <button class="ikun03">外部</button>
    <script>
      document.querySelector(".ikun02").onclick = () => {
        alert("hello ikun02");
      };
    </script>
    <script src="./js/test.js"></script>
  </body>
</html>
